Grinding wheel truing apparatus



. 6, 1960 J. w. NAREL ETAL GRINDING WHEEL mums APPARATUS 3 Sheets-Sheet 1 Filed July 30, 1958 INVENTORS ,Jb5EF'H W NAREL E QUVE E JUYEE MUD- satm ATTORNEY Dec. 6, 1960 J. w. NAREL ETAL GRINDING WHEEL mums APPARATUS 3 Sheets-Sheet 2 Filed July 30, 195B 4 2 $5 .6 W h 0 lo a 6 7 /O 5 L Fig-Z Dec. 6, 1960 I J. w. NAREL EI'AL 2,963,017

GRINDING WHEEL mums APPARATUS Filed July 30, 1958 3 Sheets-Sheet 3 INVENTORS JOSEPH W NAREL.

J5 55 45,32.) user ATTORNEY United States Patent 12,963,011 GRINDING WHEEL L'IERUING AIPQPARA'IWE Jose h W. Narel nd-Glo erslalqyss, W r e;ster ,.=Ma asS g mls to Norton Company; :Wgrcester, Mass, a corporation of Massach s tts Filed rui so, 195s, s mosrs hso 1 10 :Clairns. (Cl. '.1. -":1

The invention relates rte grinding machines, and more particularly to a grinding wheel truing apparatus.

One object of the invention is :to provide .a simple and thoroughly practical grinding wheel truing apparatusifor truing aperipheral face ofagrinding wheel which terminates in rounded edges or radii by .a continuous pass of a single truing tool thereover. Another .object ,isto

provide means to traverse the truing :tool at a substantially uniform surface speed across the periphery and around the radii of a grinding wheel atreach end of the peripheral face.

Another object is to provide a radial truing tdevlce in :which a rack and gear are movedlongitudinallyas razunit to move the truing tool at a rate suitable for truing the peripheral surf-ace and in whichthe-raclr is movedatta faster rate relative .to said gear to impart .a swinging movement to said truing. tool .at a :surface speed .substantially equal to the peripheral truing speed. -A fur- -'ther object is to provide a longitudinally movables'lide having a radial truing device and means including ::a

longitudinally movable rack and a rotatable gear on said slide and means to actuate the rack and gear mechanism so as to truea peripheral face on agrinding wheel and a radius at either end thereof. Another object is to provide yielding means to hold said :rack stationary relative to the slide during ,a traversing-movement of the slide while truing the peripheral face, ofqthe grinding wheel. Another object :to provide power operated means to control the 'yieldable means when the slide is heldagainst longitudinal movement ,to impart a lognitiudinal movement to the rack while-truing theradii.

iiOther objects will :be in part obvious .or in part pointed out hereinafter.

One embodiment of the invention has been illustrated in the drawings in which:

Fig. 4 is a fragmentary sectional view, on an enlarged scale, through the truing tool and its supporting arm and shaft;

Fig. 5 is a diagrammatic view, showing the path of movement of -t-hetruing-toolas viewed from the front of themachine; and Y *Figrfi is a combined hydraulic and'electric diagram of the actuating mechanisms and the controls therefore.

A fragment of a grinding-machine has been illustrated in the drawings comprising a-lwheel slijde lfl :whichsupportsa-wheel spindle ll .-;in.s uitableib.earings {not shown).

.Clhe grinding wheel spindle 1:1 uapo ts'a g inding whe l 1;. A .drivinamecha isr is prov ded a tl th grindins wheel and, pind samurai-as a mo or 3 moun d o 2,963,017 Patented Dec. 6, 196 0 the upper surface of thezwheel slide 1'10. The motor 13 is provided with a motor shaft 14 which supports a -m1iltiple V-groove pully 15. The pully 15 is connected 'by multiple M-belts 16"with a pulley '17 mounted .on the .wheel spindle 11 .(Fig. 1). The grinding wheel .12 is particularly surrounded byawheel guard, 18.

A truing apparatus is provided for truing a peripheral faceof a grinding @wheel which terminates in rounded edges at :each edge fonuse in'grindipgcrankpins and the dike. fltretruinglapparatusdspreferablysupported by the .wheel slide 10. The .truing apparatus'comprisesa base 20 whichisfixedly mounted onrthe'upper portion of the wheelrslide .10. Th base ,20 suppor a vertically m e- :ableislidernember 21 which is arrang d to slide vertically .on ,a dovetailed slide way 22. Alrotatable feed screw 23 is provided for adjusting the vertical slide member 121;relative:.to.,the base j10-and thereby transversely of a grinding wheel to 13nd from its axis. The feed screw 23 is rotatably journalled in anti-friction bearings 24 :mounted on the .base .20. The feed screw 23 meshes with ,orengages a nut25 which is mounted on the vertical .slide 21. .A'relativelyl-argegear .26 is keyed onto the iupperend of the feed-screw. 23 and-meshes with a small gear :27 which is fixedly mounted on a rotatable vertically arranged shatt28. The uppe e dof thesh ft 28 is p vided with a manually operable hand wheel 29 by means .of which a rotaryfeeding adjustment may be imparted :to the feed screw 23.

To facilitate holding the shaft 28 against rotary motion, a serrated wheel 30 is provided on the shaft 28. The serrated heel 301s en d y a sp n pressed detes .31. .;It will bereadil-yppparent from the foregoing disclosure-that a manual adjustment of the feed wheel 29 will be imparted through the gears 27 and 26 to impart a rotary motion to the feed screw 23 so as to cause a vertical adjustment to the slide member 21.

.A power operated mechanism is provided to facilitate vertical adjustment of the slide 21 when an extended motion of the slide 21 is required whenrsetting up the machine or when replacing a worn out grinding wheel 12 with a new wheel. This mechanism comprises a rotarytype fluid motor 35 having armotor shaft 36 which is connected by a coupling 37 with a rotatable shaft 38 (Fig. 3). The shaft 38 is providedwith a bevel gear 39 which meshes with ,a bevel gear 40 mounted on the lower end of the shaft 28 (Fig. 1). It will be readily apparent from the foregoing disclosure. that by removing the detent 31 to an inoperative position, and then starting the fluid motor 35, a rotary motion is imparted to the feed screw 23 so as to cause either an upward or downward movement to the slide member 21.

The vertical slide member 21 serves as a support for a horizontally movable slide 44 which is arranged to move in a horizontal direction relative thereto and longitudinally of theaxis of a grinding wheel on a pair of spaced anti-friction slideways 45 and 46. The horizontal-slide 44 is provided with an extension 44a (Figs. 2 and 3) which extends through an aperture .43 formed .inthe wheel guard 18.

The horizontal slide .44 supports a radial-type truing device comprising a housing 47 whichis fixedly mounted on the right hand end of the slide 44. The housing 47 contains a rotatable shaft 48 which is journalled in spaced anti-friction bearings 49 and 50. An oif-set arm 51 is mounted on the left hand end of the shaft 48 and serves as a support for a truing tool to be hereinafter described. The arm-51 supports aslidably keyed sleeve 52 which maybe clamped in adjusted position by means of a clamping screw 53. The ,sleeve52 supports ashaft 54- having a truing tool or diamond55 mounted at its lower end (Fig. 4). A feed screw 56 actuated by a the shaft 48. A rack bar 59 meshes with the pinion 58 and is slidably mounted within a cylindrical aperture 60 formed in the housing 47. The rack bar 59 is preferably split and spring loaded, as illustrated in Fig. 4, so

as to take up backlash between the rack'59 and the gear 58. This split rack is an old well known feature and consequently has not been illustrated in detail.

I A hydraulically operated mechanism is provided for imparting a longitudinal movement to the horizontal slide 44 and also to impart arotary motion to the shaft 48 so that a peripheral face may be trued on the periphery of the grinding wheel 12 having a radius formed at either edge thereof. This mechanism comprises a cylinder 65 which is supported on the vertically movable slide 20. The cylinder 65 contains a slidably mounted piston 66 which is connected to the left hand end of a piston rod 67 (Figs. 2 and 3). The piston rod 67 is connected by a stud 68 with a link 69. The link 69 is connected by a stud 70 with a rock arm 71 which is pivotally supported by a stud 72 which is carried by the slide 44.

The upper endof the rack arm 71 is a yoke-shaped portion which carries a pair of spaced blocks 73 on a pair of studs 74. The blocks 73 ride in a groove 75 formed in a spool-shaped member 76 which is fixedly mounted on a slide rod 77. The slide rod 77 is jour- -nalled in spaced bearings 78 and 79 formed in a pair of spaced bosses which are integral with the slide 44. A pair of flanged sleeves 80 and 81 are slidably mounted on the slide rod 77. A compression spring 82 surrounds the sleeves 80 and 81 and is interposed between the flanges thereon. Thus, the spring 82 tends to maintain the flanges of the respective sleeves 80 and 81 in engagement with a stop surface 83 formed at the right hand end of bearing 78 and a stop surface 84 formed at the left hand end of the bearing 79, respectively (Fig. 2). The spring 82 normally has suflicient compression to hold the rod 77 stationary relative to the slide 44 to prevent rotary movement of the radial truing arm 51 during movement of slide '44 while truing the peripheral surface C (Fig. on the grinding wheel 12. The flanged sleeve 80 is arranged to be engaged by a shoulder 77a on the slide rod 77 when rod 77 is moved toward the right. The slide rod 77 is provided with a sleeve 85 mounted thereon and constrained against movement longitudinally of the rod 77 which forms a shoulder which engages the flanged sleeve 81 as the rod 77 is moved toward the left (Fig. 2) in a manner corresponding to the engagement of flanged sleeve 80 by shoulder 77a when rod 77 is moved toward the right. When the compression of the spring 82 is released as the piston 66 moves toward the left (Fig. 2), the flanged sleeve 80 moves toward the left until it engages the stop surface 83 formed on the right hand end of the bearing 78. The sleeves 80 and 81 slide on a reduced portion 7711 on the slide rod 77. The slide rod 77 is arranged in axial alignment with the rack bar 59 and is connected thereto by a rod 86.

A dog mechanism is provided for adjustably limiting the longitudinal movement of the slide 4 4 to facilitate truing a peripheral face of the desired width on the grinding wheel 12, comprising an adjustable stop block 87 which is adjustably clamped onto the vertical slide 21 by means of a pair of clamping screws 88 and 89 which pass through elongated slots formed in the block 87 and are screw threaded into the vertical slide member 21.

48 by means of a pinion or gear 58 formed integral with A pair of spaced adjusting screws 90 and 91 are provided to facilitate a precise longitudinal adjustment of the stop block 87. The horizontally movable slide 44 is provided with a pair of spaced downwardly projecting bosses which carry a pair of spaced adjustable stop screws 93 and 94 which are to move into engagement with the stop block 87 when the slide 44 is moved longitudinally in either direction so as to limit the longitudinal movement of the slide 44. I

A fluid pressure system is provided for supplying fluid under pressure to the various mechanisms of the machine. This system comprises a motor driven fluid pump 95 (Fig. 6) by drawing fluid through a pipe 96 from a reservoir 97 and forces fluid under pressure through a pipe 98. A relief valve 99 is connected in the pipe 98 by means of which excess fluid under pressure may be passed directly to the reservoir 97 so as to facilitate maintaining a substantially uniform operating pressure within the fluid system.

A control valve 100 is provided for controlling the admission to and exhaust of fluid from the cylinder 65 and also to control the admission to and exhaust of fluid from a feed cylinder to be hereinafter described. The valve 100 is a piston type valve having a slidable valve member 101 formed with a plurality of spaced valve pistons which form a plurality of spaced valve chambers 102, 103, and 104. The slidably mounted valve member 101 is also provided with a central passage 105 which connects the valve chamber 102 with the valve chamber 104. A compression spring 106 serves normally to maintain the'valve member 101 in a left hand end position. A solenoid S1 is provided which when energized serves to shift the valve member 101 into a right hand end position to reverse the direction of flow of fluid to and exhaust of fluid from the cylinder 65.

'In the position of the valve 100 (Fig. 6) fluid under pressure from the pipe 98 entering the valve chamber 103 passes through a pipe 107, through a ball check valve 108 and also through a throttle valve 109 into a cylinder chamber 110 so as to move the piston 66 'toward the left. During this movement, fluid within a cylinder chamber 111 exhausts through a pipe 112, through a throttle valve 113, through the pipe 112 into the valve chamber 104, through the central passage 105 into the valve chamber 102 and exhausts through a pipe 116 into the reservoir 97. A ball check valve 114 is provided in the pipe line 112 so that when fluid under pressure passes in the reverse direction through the pipe 112, it may flow at a substantially unrestricted rate through both the ball check valve 114 and the throttle valve 113 into the cylinder chamber 111 to move the piston 66 toward the right (Fig. 6). It will be readily apparent from the foregoing disclosure that by manipulation of the throttle valves 109 and 113, the rate of movement of the piston 66 and the slide 44 may be readily varied as desired.

A power operated feeding mechanism is provided for automatically feed-ing the truing tool 55 toward the axis of the grinding wheel at the start of each traversing movement of the truing tool. This mechanism comprises a ratchet wheel 120 which is fixedly connected to the gear 26 so as to impart a rotary motion to the feed screw 23.

An oscillatable pawl carrying arm 121 is rotatably supported on the upper end of the feed screw 23 directly below the ratchet wheel 120. A pair of pivotally mounted pawls 122 and 122a are pivotally supported by a'stud 123 on the pawl arm 121. The pawls 122 and 122a are of slightly different lengths so that a fraction of a tooth space may be picked up on the ratchet wheel during actuation thereof. A rotatable cam or eccentric 118 is mounted on the arm 121 to facilitate rocking the pawls 122-122a out of engagement with the ratchet wheel 120 during power actuation of the vertical slide member Q :21. The pawl earm 121 is actuated :byea hydraulically operated mechanism comprising a cylinder 124 (Fig. .6) which contains aslidably mounted piston 1.25. Thepiston 125 is connected to one end of a piston rod 126. The other end of the pistonrod is arranged to engage a boss 147 formed integral with pawl arm 1 121. A com- :pression spring 127 is provided normally to hold the piston 125 in adownward position. :When fluid .under pressure is passed through a pipe'1'28 into a cylinder chamber 129, the piston 125 is moved against the comepression of the spring 127 to swing the pawl carrying arm -12-1 in a counter-clockwise direction {Fig 6).

A shuttle-type valve 13.0is providedfor controlling .the admission to and exhaust'o'f fluid frorn the cylinder charnher 129-rapidly .to actuate the feed pawls 122-122a. This valve comprises a slidable valve member 131 havinga plurality of spaced valve pistons for-med integrally -therewith'to form -a pair ofspaced valve chambers 132 -and 133. A throttle valve -1 34 is connected -in the pipe 107 to control the admission to and exhaust .of iluid j-from an-end chamber 135 in-the valve 130. *Similarly a throttle valve 137 --is connected in the pipe 112 to control the admission to and exhaust of --fiuid from an end ch-amher 136 in the-valve 130. By manipulation of the throttle "valves 134 and 137, {the ;rate of shifting of the valve member 131 may :be readily controlled. During the shiftingmovement of the valve member 131 in either direction, fluid under pressure is passed -i nstantaneously through pipe 128 to provide arapid actuation of the feed ,pawls 12 2- 125211. As soon as the valve member 131 approaches the end of its stroke in either direction, a port at the end of exhaustpipe 13 8 is opened thereby allowing fluid to exhaust from "the cylinder chamber 129, 'Ifhe released compression of the'spring'127 causes a rapid downward movement of the piston 125 and a rapid idlereturn stroke of the feed pawls 3122-1221: in a clockwise directionflinto a reset position, as shown in fig. 6. In the position illustrated in Fig. 6, the ,pipe 128 is connected with the valve chamber 133 which allows fluid to exhaust through a .pipe 138 into the reservoir 97'.

W en he solenoid stisene gized to s i t the valve member 101 toward .the right fluid .under pressure entering zt valve chamber 103 passes through the pipe 112, to start a traversing movement ,of the truing tool 55 toward the .right, fluid talsopasses through the pipe 112a into the valve chamber 132, through the pipe 1.28 so as to impart .a feeding movement tob the ratchet Wheel 12.0.

.Eluid un e .prressure passing ough t en p 112 also passes throug the thr ttle valv 1 7 into theend chamher 136. so as to shift the valve memberlSl toward the night at a rate controlled by the throttle valves 134 and ,137. During the shifting movement of the valve member 151 toward ithegright, zthe port ;a t the end of the pipe 112a is closed after which the valve ,chamber;132 is connected to-the exhaust .pipe 138 so that fluid within the cylinder chamber 129 is free 'to-exhaust therefrom under the released compression of the spring 127 so as to release the compression of a spring 148 (Fig 3) which returns the pawl arm 121 to its normal position. A pair of spaced aligned stop screws-149 and 1 5i) are provided "-10 determine the extent of oscillation of the pawl carrying -arm121 at each actuation of the piston 125. These -stop screws 149 and 150 are mounted on the truing apparatus base 20.

A-rotary type control valve 140 is provided to control the admission to and exhaust of fluid from the fluid control '35. The valve 140 is actuated by a control lever 141. A pipe 143 connects the valve 14% with one *side-ofthemotor 35. A pipe "-144 connects the valvs 140 ---with-the other side of the motor 35 and -a-pipe 145 connect-s the valve 140--with a throttle valve 146 which controlsthe-rate of exhaust offluid from the motor 35-so as .6 std-facilita e regulat n he speed of movemen of the -.motor .35- I When it is desired to raise or lower the verticalslide member 21 to facilitate setting up the machine, or for repositioning h ru n apparatus when a n o ing .wheel 1 2-is;replaced with a new grinding wheel, -.a manually operable cam 113 on the arm 1,21is rotated to rock-the pawls 122-12241 out of engagement with the ratchet wheel after which the .control lever 141 may be shifted .in la counter-clockwise direction into broken line position 141a ,to tartthe motor,35 in one direction .to rotate the feed screw 23 to ra se the vertical slide ,21. Or the .eontr lilever 1 .13 6 eshiftedin a clockwise direction into broken line'position 141a so as to start the ifiuid motor 35 in the reverse direction to rotate the feed screw 23 ,so as to cause a downward movement .of the vertical slide member ,21.

It is desirable to maintain a substantially uniform peripheral :speed of the grinding wheel ;12-as tilt wears .away during grinding. This is Preferably accomplished :by providing .a variable speed grin ing whe l d i g -motor 13 which-is controlled by arheostat1 5-5 (Figs. 1,

truing tool 55: relative ;to the axis .of the grinding wheel 12 will be imparted through therack bar 158 and the gear 15710 actuate the rheostat 1'55 soastomaintain a substantially uniform peripheral speed of the grinding wheel 12 .as it wears away.

When a truing operation is initiated,tthezslide 44 re- :mains stationary and the rack bar 59 moves longitudinalto impart a rotary motion to theshat't .48 .toswing the arm 51 and truing tool 55 through angles A .and .BJ During this movement the truning tool 55 movesinto operative engagement with the side face of the grinding wheel 12 and trues a radius 12a on the corner of the grinding wheel (Fig. 5). When the truing .tool reaches position 55a, the rack bar 59 remains stationary relative to the ,slide 44 as the slide 44.moves longitudinally toward the right to true a peripheral surface 12b while ithetruing tool traverses through the distance C (Fig. .5). The slide 44 then remains stationary and the rack 1381159 moves longitudinally relative to theslide .44 toiswing ithe truing tool 55 through angles B and A so as to truea radius 12c on the grinding wheel 12 stopping the truing tool in the position 550 out of engagement with the side face of the grinding wheel.

In order to obtain a uniform tming operation across the face of the grinding wheel and around the corners at the ends thereof, it is desirable to move the truing. tool 55 at a substantially uniform rate around the corners and across the peripheral surface of the wheel. In order *to obtain a substantially uniform speed of the truing tool while truing the radii at the corners of the grinding wheel, it is necessary to speed-up the motion of the rack bar 59 so that the truing tool 55 travels around the corners of the wheel at a rate substantially the same as the longitudinal traversing movement of the slide 44. This is preferably accomplished bythe connection between the piston rod 67 and the slide'rod 77. The lever arm between the axis of the stud 72 and the stud 70 (Fig. 2) forms a relatively shortlever arm whereas the distance between the axis of the stud 72 and the axis of the slide rod 77 is several times greater, namely, 3 /2 or 4 to 1 so that when the piston 66-moves the slide 44 together with the rod 77 will move at a desiredgrate ,for peripheral truing. During the truing of the radii, the rod 77 is arranged to move at a-fasterrate due to 3% or 4 to 1 lever arms relative to the movement of the piston 66 so'tha-t the truing speed of the truing tool "55 as it 7 rounds the radii approximates the speed of movement of the slide 44 while truing the peripheral surface of the wheel.

The operation of the improved truing apparatus will be readily apparent from the foregoing disclosure. The throttle valves 109 and 113 are adjusted to give a predetermined speed to the piston 66, the slide 44 and the truing tool 55 to give the desired truing action while the truing tool 55 is traversing between positions 55a and 55b (Fig. The throttle valves 134 and 137 are adjusted to regulate the rate of shifting movement of the valve member 131 and the stop screws 149 and 150 are adjusted so that a predetermined number of teeth of the ratchet wheel 120 are picked for each actuation of the pawls 122 and 122a. The switch SW1 is then closed to start the fluid pump 95 to supply fluid under pressure to the system. Switch SW2 is closed to start the wheel driving motor 13.

The truing cycle stops with the truing tool 55 at one end of its stroke in position 55 (Fig. 5) and with the slide 44 positioned at one end of its stroke with the stop screw 92 in engagement with the stop block 87. As shown in Fig. 6, the slide 44 together with the truing tool 55 are stopped at the end of a truing cycle in a left hand end position (Figs. 5 and 6) with the spring 82 compressed by the flanged sleeve 80.

When it is desired to start a truing cycle, the push button switch PBl is momentarily closed to close a circuit so as to energize relay switch CR1 to close the normally open contacts a and b. The closing of contacts b of switch CR1 serves to set-up a holding circuit through the normally closed contacts of a limit switch LS1 to maintain the relay switch CR1 energized after the push button switch PBl is released. The closing of contacts a of relay switch CR1 serves to energize the solenoid S1 to shift the valve member 101 into a right hand end position so that fluid under pressure entering the valve chamber 103 passes through the pipe 112, through the throttle valve 113 and the ball check valve 114 into the cylinder chamber 111 to start the piston 66 moving toward the right (Fig. 6) so as to start a swinging movement to the rock arm 71 in a counter-clockwise direction (Fig. 6). This movement of the rock arm 71 serves to move the rod 77 toward the right thereby imparting a corresponding movement to the rack 59 to rotate the gear 58 in a clockwise direction (Fig. 6). This movement of the rack bar 59 serves to impart a swinging movement to the radial truing arm 51 thereby swinging the truing tool 55 in a clockwise direction from position 55 into position 55a. During the first part of this movement when the truing tool moves through angle A the truing tool is out of engagement with the grinding wheel. During the latter part of the swinging movement of the truing tool, the truing tool 55 engages the operative face of the grinding wheel and trues a radius 12a. The movement of the rod 77 toward the right (Fig. 6) is produced by the released compression of the spring 82 as governed by the movement of the piston 66. The swinging movement of the truing tool continues until the flanged bushing 80 engages the stop surface 83 and the sleeve 85 engages the bushing 81 at which time the slide 44 starts its traversing movement toward the right to traverse the truing tool from position 55a into position 55b (Fig. 5) that is through the distance C to true the peripheral face 12b. The ends of the traversing movement of the truing tool 55 and slide 44 while truing the peripheral face are determined by the adjustment of the stop screws 92 and 93.

When the truing tool 55 reaches position 55b (Fig. 5), the stop screw 93 engages the left hand end face of the stop block 87 which stops the longitudinal movement of the slide 44. During the longitudinal movement of the slide 44, the rack bar 59 together with the rod 77 are held against endwise movement relative to the slide 44 by the compression of the spring 82. The spring 82 is at all times under compression sufficient to prevent movement 8 of rod 77 and rack bar 59 relative to the slide during the longitudinal traversing movement of the slide 44. The spring 82 is further compressed when rod 77 and rack 59 are moved longitudinally in either direction relative to the slide 44 during the truing of the radii 12a and 12a.

Continued movement of the piston 66 toward the right causes the sleeve 85 to further compress the spring 82 as the rack bar 59 swings the arm 51 and the truing tool 55 in a clockwise direction from position 55b into position 550, through angles B and A to true the radius 12c and move the truing tool 55 out of engagement with the grinding wheel 12. The movement of the sleeve 81 toward the right continues compressing the spring 82 until the right hand end of the sleeve 81 engages the left hand end of the sleeve 80 thereby stopping the longitudinal movement of the rod 77 and the rack 59 relative to the slide 44, and also stopping the swinging movement of the arm 51 and the truing tool 55 with the truing tool out of engagement with the side face of the grinding wheel 12 (Fig. 5).

When the truing tool reaches the position 556 (Fig. 6) an adjustable collar 165 carried by the extension 166 of the rod 77 engages the actuating roller of the limit switch LS1 to open the contacts thereof thereby breaking the holding circuit so as to deenergize relay switch CR1 and thereby to deenergize the solenoid S1. When the solenoid S1 is deenergized, the released compression of the spring 106 shifts the valve member 101 toward the left into the position illustrated in Fig. 6. In this position of the valve 100, fluid entering the valve chamber 103 passes through the pipe 107, through the throttle valve 109 and the ball check valve 108 into the cylinder chamber 110 (Fig. 6) so as to start the movement of the piston 66 toward the left (Fig. 6).

In this position of the parts, it should be remembered that the slide 44 is positioned at the right hand end of its stroke (Fig. 6) with the stop screw 93 engaging the stop block 87. As the piston 66 moves toward the left, the rock arm 71 swings in a clockwise direction thereby releasing the compression of the spring 82 during which movement the rack bar 59 moves toward the left relative to the slide 44 so as to swing the frame 51 and the truing tool 55 in a counter-clockwise direction to start the traversing movement of the truing tool 55 in the opposite direction from the position 55c (Fig. 5) through positions 55b and 5511, into position 55 thereby traversing the truing tool about the radius 12c across the peripheral face 12b, and around the radius 12a. When the stop screw 92 engages the stop block 87, it terminates movement of the slide 44 toward the left. Continued movement of the piston 66 toward the left shifts the rod 77 toward the left. A shoulder 77a, on the rod 77 engages the flanged sleeve 80 and starts compressing the spring 82 as the radial truing arm 51 swings the truing tool 55 in a counterclockwise direction to true the radius 12a (Fig. 5) on the grinding wheel 12. The radial arm 51 continues its movement in a counter-clockwise direction until the left hand end of the flanged sleeve 80 engages the right hand end of the flanged sleeve 81 which serves as a stop to terminate the swinging movement of arm 51 with the truing tool 55 in position 55 out of engagement with the side face of the grinding wheel 12.

The arm 51 together with the truing tool 55 and other associated parts remains in the position as illustrated in Fig. 6 until a new truing cycle is initiated by again momentarily closing the switch PB1.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accom- 9 mi it as tabs int r reted cillustratixe and a tnmsssen een din mash n ttachmen for .causiag a t uin m lt r-bsrmot acrassthep r nh ra can a -stindiiig whee which sun-face termina es i sma l .ra iat i ed es sa d a achmen su p ns iasl dab s suppo t, a tu in tcc secured to a a ,al ru as r t tabh mcumed ,un n aid suppor a ,gear h any a t k he: m sh ng with .said, sear ..d fieru ally gps ahle actu t uaim ans ,opera 1e .at a first spficd is 4 19 sa rac 9a, 'tus 'sa y relat ve tv sa dlsi ppg t to impede ota y motion t thesea t c use he t gs-to t more e eion c the then cramble at secqa spe t to m re th rack a gea ilcns tu- .dina iy a a u i w h sai rsu p tin a e i, ct sm' len hof th r c t9 cause th tr in t pl to. more e the p riph ral u tas Q asr u n wheel fiu j y tort-sabl st lt m t sp d impa t, tur he loug tudinal t v mem to s i a k than? t s d su p ife rqt ti g t e gea to cause the twins too to sm e over the other radius on the grinding wheel, said differentially operable actuating means being arranged to move aid ra k relative to sai s ppdtt .a fa rate than during he,longi tudinal ,moveri entpf the rack and gear as a unit'in order to rotate said gear at a rate such that thesurface speed of the .trtuingztool is substantially uniform throughout-its path ,of moyement around the ,i adii and across the periphery of agrinding wheel.

A grinding machine, aslcl airned -in-claim -1,wherein said differentially operable actuating means includes a fluid motor to traverse said rack and gear as a unit with said support to traverse the truing tool across the perip'hery of the grinding wheel, adjustable stops to limit the longitudinal movement of said rack and gear as a unit with said support, and operative connections between said motor and said rack to move said rack relative to said support at a faster speed than the motor while truing the radii.

3. A grinding machine having a rotatable grinding wheel, a truing apparatus base, a transversely movable slide member on said base which is arranged to move toward and from the axis of the grinding wheel, a longitudinally movable slide on said slide member, means to traverse said slide longitudinally, a radial truing arm rotatably supported on said longitudinally movable slide, a truing tool on said arm, means to adjust the truing tool relative to the arm to vary the radius generated thereby, means to limit the longitudinal movement of said slide to facilitate truing a peripheral face of a predetermined extent on the grinding wheel, means to impart a relative transverse feeding movement to said transversely movable slide member at the start of each traversing movement of said longitudinally movable slide, a gear on said arm, a rack bar slidably mounted}:

on the longitudinal slide which meshes with said gear,

and differentially operable actuating means interconnecting said slide member, said slide and said rack, including a motor operatively connected to move said rack relative to said slide at a first predetermined rate to rotate said gear and thereby cause the dressing tool to true'a radius on one edge of said grinding wheel, said motor being arranged thereafter to move said rack and slide as a unit with said slide at a second predetermined rate to cause the truing tool to true the peripheral face of the grinding wheel, said motor being arranged there'- aft er to move said rack relative to said slide at said first predetermined rate to cause the truing tool to true a radius on the other edge of the grinding wheel so that grinding wheel at a substantially uniform surface speed I during the entire truing operation.

A grinding machine, as claimed in claim 3, in

. .70 the truing tool moves across the operative face of the.

sesame pfji eldable rneans normally to hold; sziid-rack-stationai y rela ve-its sa d l e-dur h g ud a movement of the s li de, and ,means including fadjustable stops=:to limit the movement of said slide to determinetheemtent of the I peripheral truing operation, said actuating means also including means operable'when said-slideengages a stop tomove said rack longitudinally relative to the slide at a rate faster than thenormalfmovement of the slide ,so as to speed-up movement of the-truing tool while truing a radius so that the surfacespeed of the t-ruing tool is substantially uniform during the-entiretruingopsta o 5. A grinding machine, as claimed -in-claim'3, in combination with theparts and features therein specified o a c mpr n sp ne rt a ly to ld a c stationary-relative to said slidesothat the rack and slide ,move a unit during longitudinal movement of the slide to .tnaverse the truingtool across the'peripheral {face pfthe grinding wheel, and means including-adjustable stop dogs to limit the longitudinal movement of 'thCjSiiEiQE, said differentially operable actuating-means arranged to overpower said spring'before andafter the peripheral t ruing operationto move saidrack longitudinally relative to said slide at a faster rate thanthe longitudinal movement of the slide during the peripheral truingoperw tion to true a radius at each end of "the-peripheral face while the truing tool swings at a substantially uniform sur ace sp e 6. A grinding machine as claimed in claim'-3,-wherein' slide, operative connections between'said motor and a short arm of said lever, operative connections between a long arm of said lever and said rack, yieldable means between the rack and slide to hold the rack stationary relative to the slide during longitudinal movement of said slide for a peripheral truing operation, and adjustable stop screws to limit the longitudinal movement to the slide, said operative connections serving to cause a longitudinal movement of said rack relative to said slide at a faster rate than movement of the slide so as to impart a swing movement to said truing tool to true radii on said wheel at substantially the same surface speed as during the peripheral truing operation.

7. A grinding machine attachment for causing a truing tool to be moved across the peripheral surface of a grinding wheel which surface terminates in radii at its edges, said attachment comprising a truing tool secured to a rotatably mounted radial truing arm, a gear on said arm, a rack bar meshing with said gear, differentially operable actuating means to move said rack longitudinally relative to said truing arm to impart a rotary motion to the gear so as to cause the truing tool to move over one of the radii, then operable to move the rack and the truing arm longitudinally as a unit in a direction lengthwise of the rack to cause the truing tool to move over the peripheral surface of a grinding wheel, and finally operable to impart a further longitudinal movement to said rack relative to said truing arm for rotating the gear to cause the truing tool to move over the other radius on the grinding wheel, said differentially operable actuating means including means for moving the rack longitudinally relative to said truing arm at a rate relative to that during the longitudinal movement of said rack and said truing arm as a unit to rotate said gear such that the surface speed of the truing tool is substantially uniform throughout its path of movement.

8. A grinding machine attachment for causing a truing tool to be moved across the peripheral surface of a grinding wheel which surface terminates in radii at its edges, said attachment comprising a relatively fixed support, a supporting means slidably mounted upon said fixed support, a truing tool secured to a radial truing arm rotatably mounted upon said supporting means, a gear fixedly secured to said arm for rotation therewith, a rack bar;

meshing with said gear mounted for sliding movement both with and relative to said supporting means, spaced opposed stop means to limit sliding movement of said supporting means, differentially operable actuating means selectively operable to move said rack and said supporting means concurrently at a first predetermined rate between said stop means and to move said rack relative to said supporting means at a second predetermined rate to rotate said gear when said supporting means is in engagement with one of said stop means, said first and second predetermined rates being selected so that the surface speed of the truing tool is substantially constant across the peripheral surface and the respective radii.

9. A grinding machine attachment as described in 'claim 8, wherein said diiferentially operable actuating means includes a substantially constant speed drive means, a linkage arranged for concurrent translational and angular displacement interconnecting said drive means'and said rack and said supporting means, and resiliently biased means arranged to restrain said linkage means against angular displacement while said supporting means is moving between said stop means.

10. A grinding machine having a rotatable grinding wheel, a truing apparatus base, a transversely movable slide member on said base which is arranged to move toward and from the axis of the grinding wheel, a longitudinally movable slide on said slide member, means to tnaverse said slide longitudinally, a radial truing arm rotatably supported on said longitudinally movable slide, a truing tool on said arm, means to adjust the truing tool relative to the arm to vary the radius generated thereby, means to limit the longitudinal movement of said slide to facilitate truing a peripheral face of a predetermined extent on the grinding wheel, meansjo impart a relative transverse feedingmovement tosaid transversely movable slide member at the start of eachtraversing movement of said longitudinally movable slide, a gear on said arm, a rack bar slidably mounted on the longitudinal slide which meshes with said gear, and means including a motor, a pivotally mounted lever on said longitudinally movable slide, operative connections between said motor and a short arm of said lever, operative connections between a long arm of said lever and said rack, yieldable means between the rack and slide to hold the rack stationary relative to the slide during longitudinal movement of said slide for a peripheral truing operation, and adjustable stop screws to limit the longitudinal movement to the slide, said operative connections serving to cause a longitudinal movement of said rack relative to said slide at a faster rate than move ment of the slide so as to impart a swinging movement to said truing tool to true radii on said wheel at substantially the same surface speed as during the peripheral truing operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,294,492 Wilson Sept. 1, 1942 FOREIGN PATENTS 540,588 Great Britain Oct. 22, 1941 494,704 Great Britain Oct. 31, 1958 

